JP2552348B2 - 4-wheel steering system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a four-wheel steering device in which steering of front wheels is transmitted to rear wheels via a cable.

<Prior Art> Such a four-wheel steering device is known, for example, from Japanese Utility Model Laid-Open No. 60-15052, which transmits the movement of the front wheels to a gear of a rear-wheel steering device via a cable to rotate the gears. Is transmitted to the rack to steer the rear wheels in reverse phase to the front wheels.

<Problems to be Solved by the Invention> In the above, since the steering angle of the rear wheels linearly increases in proportion to the steering angle of the front wheels, a cubic curve like that shown in FIG. 6 is obtained. I can't. Therefore, since the rear wheels are steered even if the steering angle of the front wheels is small, there is a problem that it is not suitable for high speed running.

<Means for Solving the Problems> The present invention has been made to solve the above-mentioned problems, and rotatably supports a rear wheel output shaft in a rear wheel housing of a rear wheel steering device. The rear wheel side input shaft, through which the operation of the front wheel steering device is transmitted to the cable, is rotatably supported at a position eccentric to the output shaft, and a radial engagement groove is formed in the input shaft to engage with the engagement groove. An eccentric pin is mounted on the output shaft eccentric from the rotation center of the output shaft by an amount larger than the eccentric amount of the input shaft and the output shaft.

Also, the front wheel side input shaft is rotatably supported in the front wheel housing of the front wheel steering system, and the front wheel side output shaft, which transmits the operation of the front wheel steering system to the cable, is rotatably supported in a position eccentric to the input shaft. Then, the radial engagement groove is formed on the input shaft, and the eccentric pin that engages with the engagement groove is provided on the output shaft eccentric from the rotation center of the output shaft by an amount larger than the eccentric amount of the input shaft and the output shaft. Install.

<Operation> In the rear wheel steering device provided with the engagement groove and the engagement pin, when the front wheels are steered by the front wheel steering device, the steering of the front wheels is transmitted to the input shaft of the rear wheel steering device via the cable, The rotation of the input shaft is transmitted to the output shaft via the engagement groove and the engagement pin. Then, the eccentric pin attached to the position of the output shaft which is eccentric from the rotation center of the output shaft moves while engaging with the engagement groove with an eccentric amount larger than the eccentricity of the rotation center of the input shaft and the output shaft. Therefore, as the input shaft rotates, the output shaft rotates less at the beginning and largely rotates at the end. The rear wheels are steered by the rotation of the output shaft. Further, in the case where the front wheel steering device is provided with the engagement groove and the engagement pin, when the front wheels are steered by the front wheel steering device, the steering of the front wheels is transmitted to the input shaft of the front wheel steering device, and the rotation of the input shaft is engaged. It is transmitted to the output shaft via the groove and the engaging pin. Then, the eccentric pin attached to the position of the output shaft that is eccentric to the rotation center of the output shaft engages with the engagement groove and moves with an eccentricity that is larger than the eccentricity of the rotation center of the input and output shafts. Because
With the rotation of the input shaft, the output shaft rotates less at the beginning, and rotates largely at the end. The rotation of the output shaft is transmitted to the rear wheel steering device via a cable to steer the rear wheels.

<Examples> Examples of the present invention will be described below with reference to the drawings. Second
In the figure, 10 is a front wheel rack shaft, and front wheels 13 are connected to both ends of the front wheel rack shaft 10 via tie rods 11 and knuckle arms 12. A rack 14 is formed on the front wheel rack shaft 10, and the front wheel pinion shaft is formed on the rack 14.
15 pinions 16 are meshed. The pinion shaft 15 is rotatably connected to the handle 18 via a rotary valve 17. A piston 20 that slides in a cylinder tube 19 is attached to the front wheel rack shaft 10. The front wheel steering device includes the front wheel rack shaft 10, the pinion shaft 15, the rotary valve 17, the cylinder tube 19 and the piston 20 described above.
21 are composed.

25 is a rear wheel rack shaft, and the rear wheel rack shaft 25 is provided with tie rods 26 and knuckle arms 27 at both ends of the rear wheel rack shaft 25.
28 are connected. A rack 29 is formed on the rear wheel rack shaft 25, and a pinion 31 of a rear wheel pinion shaft 30 is meshed with the rack 29. The pinion shaft 30 is rotatably connected to a pulley 35 via a rotary valve 32, an assist delay avoidance device 33, and a steering characteristic device 34. The rear wheel rack shaft 25 has a piston 37 sliding in a cylinder tube 36.
Is installed. A rear wheel steering device 38 is configured by the rear wheel rack shaft 25, the pinion shaft 30, the rotary valve 32, the assist delay avoidance device 33, the steering characteristic device 34, and the pulley 35 described above.

One ends of two cables 40 and 41 are connected to both ends of the front wheel rack shaft 10, and the other ends of the two cables 40 and 41 are respectively wound around a pulley 35. An intermediate roller (not shown) is provided in the middle of the two cables 40 and 41, and the intermediate roller limits the place where the cables 40 and 41 pass. A cable length adjusting device 42 is provided in the middle of the two cables 40 and 41 in order to absorb the bending caused by the extension of the cables 40 and 41.

Reference numeral 45 denotes an automobile engine, and the PS pump 46 is driven by the engine 45. PS pump
The oil drawn up from the reservoir 47 by the 46 is diverted by the shunt control valve 48, one of the diverted oil is guided to the rotary servo valve 17 on the front wheel side, and the other diverted oil is the rotary servo valve on the rear wheel side. I am led to 32. Each rotary servo valve 17,32 is a cylinder tube 1
It is connected to the left and right chambers of 9,36 and is also connected to the reservoir valve 47.

In FIG. 1, reference numeral 50 denotes a rear wheel housing for a rear wheel steering device 38, and a rear wheel rack shaft 25 is inserted into the rear wheel housing 50. Also, the rear wheel housing 50
The pinion shaft 30 is rotatably supported around an axis line substantially orthogonal to the rear wheel rack shaft 25, and one end of a torsion bar 51 is connected to the pinion shaft 30. The other end of the torsion bar 51 is connected to an operating shaft 52, and the operating shaft 52 is rotatably supported by the rear wheel housing 50 and the pinion shaft 30. An inner valve 53 of the rotary valve 38 is integrally formed on the operating shaft 52, and an outer valve 54 of the rotary valve 38 is connected to the pinion shaft 30 via a pin 55. A first rotary member 56, a second rotary member 57, and a third rotary member (output shaft) 58 are rotatably supported on the rear wheel housing 50 so as to be rotatable coaxially with the pinion shaft 30, and an operating shaft 52 and a first rotary member. It is rotatably connected to 56 via a pin 59. A first engaging member 60 is rotatably supported by the first rotating member 56, and the first engaging member 60 is a first rotating member that protrudes in the radial direction in FIG.
The projection 56a of 56 is engaged in the clockwise direction, and the projection 57a of the second rotating member 57 protruding radially inward is engaged in the clockwise direction. A second engaging member 61 is rotatably supported by the third rotating member 58, and the second engaging member 61 is rotated clockwise on a protrusion 57b of the second rotating member 57 that protrudes radially inward in FIG. And a pin 58a protruding from the end surface of the third rotating member 58 in a clockwise direction. A first spiral spring 62 is arranged between the first rotating member 56 and the second rotating member 57,
The outer end of the first spiral spring 62 is connected to the first rotating member 56 and the second rotating member 56.
The rotary member 57 is engaged in the counterclockwise direction in FIG. 4, and the inner end of the first spiral spring 62 is engaged in the first engaging member 60 in the clockwise direction. A second spiral spring 63 is disposed between the second rotary member 57 and the third rotary member 58, and the outer end of the second spiral spring 63 is attached to the second rotary member 57 and the third rotary member 58 as shown in FIG. It is engaged clockwise and the inner end of the second spiral spring 63 is the second engaging member.
61 is engaged clockwise. By the first rotating member 56, the second rotating member 57, the third rotating member 58, the first engaging member 60, the second engaging member 61, the first spiral spring 62, and the second spiral spring 63, the rear wheel is removed to remove the rear wheel. An avoidance device 33 at the time of assist delay is configured to release the force pulling the cables 40 and 41 when the steering wheel 28 is not steered.

An eccentric pin 65 is attached to the third rotating member 58 at a position eccentric from the rotation center of the third rotating member 58 by A, in parallel with the rotation axis of the third rotating member 58, and the eccentric pin 65 is a rotatable roller. It has a 65a. A pulley (input shaft) 35 is rotatably supported in the rear wheel housing 50 at a position eccentric from the rotation center of the third rotation member 58 by B, parallel to the rotation axis of the third rotation member 58. The eccentric pin 65 is attached to the pulley 35.
5, an engagement groove 66 is formed in the radial direction as shown in FIG. 5. The engagement groove 66 is formed in the neutral state of the pulley (input shaft) 35 and the third rotating member (output shaft) 58. It is formed on a line connecting the rotation center of 35 and the rotation center of the third rotation member 58. The eccentricity amount A is set to be larger than the eccentricity amount B. A cable 40 and a cable 41 are wound around the pulley 35, respectively. The third rotation member (output shaft) 58, the eccentric pin 65, the engagement groove 66, and the pulley (input shaft) 35 constitute a steering characteristic device 34, and the steering characteristic device 34 has a rotation angle of the output shaft 58 relative to a rotation angle of the input shaft 35. The characteristics can be changed as shown in FIG. That is, when the rotation angle of the input shaft 35 is small, the output shaft 58 hardly rotates. When the rotation angle of the input shaft 35 increases,
Steering characteristics are obtained such that the rotation angle of the output shaft 58 sharply increases.

Next, the operation will be described based on the configuration described above.
When the steering wheel 18 is steered, steering of the steering wheel 18 is transmitted to the input side of the rotary valve 17, and when relative rotation occurs between the input side of the rotary valve 17 and the pinion shaft 15, the oil shunted by the shunt control valve 48 is released. It is supplied to one chamber of the cylinder tube 19. As a result, the front wheel rack shaft 10 axially moves in the direction of arrow H, the front wheel 13 is steered clockwise in FIG. 2, and the oil discharged from the other chamber of the cylinder tube 19 passes through the rotary valve 17. It is collected in the reservoir 47. The axial movement of the front wheel rack shaft 10 pulls one of the cables 40 and 41 and loosens the other. Pulley one of the cables 40, 41
The 5 rotates in one direction, and the rotation of the pulley 35 pulls the other of the cables 40 and 41. Further, the rotation of the pulley 35 causes the third rotating member 58 to pass through the engagement groove 66 and the eccentric pin 65.
The rotation of the third rotating member 58 is transmitted to the operating shaft 52 via the second spiral spring 63, the second rotary member 57, the first spiral spring 62, the first rotary member 56 and the pin 59. Working axis
The rotation of 52 is transmitted to the torsion bar 51 and the pinion shaft 30, and when relative rotation occurs between the operating shaft 53 and the pinion shaft 30, the rotary valve 38 operates and the oil diverted by the shunt control valve 48 is transferred to the cylinder tube. Supplied to one of the 36.
As a result, the rear wheel rack shaft 25 is axially moved in the direction of arrow J, and the rear wheel 28 is steered in the opposite direction to the front wheel 13, that is, counterclockwise in FIG. When the vehicle is traveling at high speed, the steering angle of the steering wheel 18 is small.
However, the rear wheel 28 is not steered. Conversely, when the vehicle is traveling at low speed, the steering angle of the steering wheel 18 is large, so the steering characteristic device 34
The third rotating member 58 is rotated by a large amount, and the rear wheel 28 is the front wheel.
It is steered in a direction opposite to 13.

With the rotation of the operating shaft 52 blocked by the removal of the rear wheel 28 or the like, the steering wheel 18 is steered to rotate the third rotation member 58 and the pin.
When 58a is rotated clockwise in FIG. 3, the outer end of the second spiral spring 63 rotates clockwise. As a result, the second rotating member 5 is attached to the inner end of the second spiral spring 63 via the protrusion 57b.
A force to rotate 7 in the clockwise direction is applied, and in addition, in FIG.
Then, a force to rotate the first rotating member 56 clockwise acts. When the forces of the first spiral spring 62 and the second spiral spring 63 are the same, the second rotating member 57 is the third rotating member.
Rotate 1/2 in the same direction as 58, and the first and second spiral springs 62,
The winding amount of 63 increases.

On the contrary, when the rotation of the operating shaft 52 is blocked by the removal of the rear wheel 28 or the like, the steering wheel 18 is steered to rotate the third rotating member 58 and the pin 58a counterclockwise in FIG. The inner end of the spring 63 rotates counterclockwise. As a result,
A force for rotating the second rotating member 57 in the counterclockwise direction acts on the outer end of the second spiral spring 63, and the first rotating member 56 is rotated through the first spiral spring 62 in FIG. A force that tries to rotate clockwise acts. Therefore,
The second rotating member 57 rotates 1/2 in the same direction as the third rotating member 58, and the winding amount of the first and second spiral springs 62, 63 increases.

7 and 8 show another modification of the front wheel steering system.
21 shows an example in which an avoidance device 71 for assist delay and a steering characteristic device 70 are provided, and the axial movement of the front wheel rack shaft 72 is performed by the intermediate pinion shaft 73, the steering characteristic device 71, and the avoidance device 70 for assist delay. And transmitted to the rotary valve 38 for the rear wheels via the pulley 74 for the front wheels, the cables 75 and 76, and the pulley 77 for the rear wheels. A front wheel rack shaft 72 is inserted through the front wheel housing 80, and an intermediate pinion shaft (input shaft) 73 meshing with the front wheel rack shaft 72 is rotatably supported by the front wheel housing 80. The front wheel housing 80 also has an intermediate pinion shaft.
The first rotary member (output shaft) 81, the second rotary member 82, and the third rotary member 83 are rotatably supported at a position eccentric from the center of rotation of 73 by an axis parallel to the rotary axis of the intermediate pinion shaft 73. Has been done. An engaging groove 84 is formed in the intermediate pinion shaft 73 in the radial direction, and an eccentric pin 85 engaging with the engaging groove 84 is eccentric to the first rotating member 81 by M from the center of rotation of the first rotating member 81. Installed on. The eccentric amount L is smaller than the eccentric amount M. A first spiral spring 86 is arranged between the first rotary member 81 and the second rotary member 82, and a second spiral spring 87 is arranged between the second rotary member 82 and the third rotary member 83. A front wheel pulley 74 is formed integrally with the third rotating member 83.

<Advantages of the Invention> As described above, according to the present invention, the output shaft and the input shaft are rotatably supported by the housing in a state of being eccentric to each other, and the input shaft is formed with the engagement groove in the radial direction. The eccentric pin that engages with the output shaft is attached to the output shaft at a position eccentric with respect to the output shaft by a larger amount than the eccentric amount of the output shaft with respect to the input shaft. Since it is hardly steered, it is suitable for high-speed driving.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a sectional view of a rear wheel steering system, Fig. 2 is an overall system diagram of a four-wheel steering system, and Fig. 3 is a III-III line in Fig. 1. Cross section,
4 is a sectional view taken along line IV-IV in FIG. 1, FIG. 5 is a sectional view taken along line VV in FIG. 1, FIG. 6 is a steering characteristic diagram, and FIG. 7 is another modification. FIG. 8 is an overall system diagram of a four-wheel steering system as an example, and FIG. 8 is a sectional view of a front wheel steering system as another modification. 10, 72 ...... front wheel rack shaft, 13 ...... front wheel, 17 ...... rotary valve, 19 ...... cylinder tube, 20 ...... piston, 21 ...... front wheel steering device, 25 ...... rear wheel rack shaft, 28 ...
… Rear wheel, 30 …… Rear wheel pinion shaft, 32 …… Rotary valve, 33,71 …… Avoidance device when delaying assist, 34,70…
… Steering characteristic device, 35 …… Pulley (input shaft), 36 …… Cylinder tube, 38 …… Rear wheel steering device, 40,41,75,76…
… Cable, 50 …… Rear wheel housing, 51 …… Torsion bar, 52 …… Actuating shaft, 58 …… Third rotating member (output shaft), 65,85 …… Eccentric pin, 66,84 …… Engagement Groove, 73 ……
Intermediate pinion shaft, 80 …… front wheel housing, 81 …… first
Rotating member (output shaft).

Front Page Continuation (72) Inventor Renjo Kato 1-1-1, Asahi-cho, Kariya City, Aichi Toyota Koki Co., Ltd. Yasuaki Yamauchi (56) Reference JP-A-63-154469 (JP, A) Sho 63-258271 (JP, A)

Claims (2)

(57) [Claims] 1. A four-wheel steering system comprising a front-wheel steering system for steering front wheels and a rear-wheel steering system for steering rear wheels, wherein the operation of the front-wheel steering system is transmitted to the rear-wheel steering system via a cable. A rear wheel output shaft is rotatably supported in the rear wheel housing of the rear wheel steering device, and the rear wheel input shaft through which the operation of the front wheel steering device is transmitted to the cable is the output shaft. The input shaft is rotatably supported at an eccentric position, a radial engagement groove is formed in the input shaft, and an eccentric pin that engages with the engagement groove is provided in a larger amount than the eccentric amount of the input shaft and the output shaft. A four-wheel steering device mounted on the output shaft eccentric from the center of rotation of the output shaft. 2. A four-wheel steering system comprising a front-wheel steering system for steering front wheels and a rear-wheel steering system for steering rear wheels, wherein the operation of the front-wheel steering system is transmitted to the rear-wheel steering system via a cable. The front wheel input shaft of the front wheel steering device is rotatably supported by the front wheel housing, and the front wheel output shaft to which the operation of the front wheel steering device is transmitted is transmitted to the cable at a position eccentric to the input shaft. The input shaft is rotatably supported, a radial engagement groove is formed in the input shaft, and an eccentric pin engaging with the engagement groove is provided in the output shaft in an amount larger than the eccentric amount of the input shaft and the output shaft. A four-wheel steering device mounted on the output shaft eccentric from the center of rotation.